Substance detection, inspection and classification system using enhanced photoemission spectroscopy

ABSTRACT

A handheld or portable detection system with a high degree of specificity and accuracy, capable of use at small and substantial standoff distances (e.g., greater than 12 inches) is utilized to identify specific substances and mixtures thereof in order to provide information to officials for identification purposes and assists in determinations related to the legality, hazardous nature and/or disposition decision of such substance(s). The system uses a synchronous detector and visible light filter to enhance detection capabilities.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.13/064,626, filed on Apr. 4, 2011 which is a Continuation-In-Part ofU.S. patent application Ser. No. 11/822,020, filed on Jun. 29, 2007,which claims the benefit of U.S. Provisional Patent Application No.60/817,101, filed on Jun. 29, 2006, both of which are herebyincorporated by reference.

FIELD OF THE INVENTION

The invention relates generally to the field of substance and materialdetection, inspection, and classification at wavelengths betweenapproximately 200 nm and approximately 1800 nm. In particular, ahandheld Enhanced Photoemission Spectroscopy (“EPS”) detection systemwith a high degree of specificity and accuracy is utilized to identifyspecific substances and mixtures thereof in order to provide informationto officials for identification purposes and assists in determinationsrelated to the legality, hazardous nature or disposition decision ofsuch substance(s).

DISCUSSION OF THE RELATED ART

Ultraviolet to Near Infrared (“UV to NIR”) EPS is an analyticaltechnique used to identify and characterize chemical and biologicalmaterials and compositions. Modern light sources and detectors have madetrue handheld operation (as opposed to “transportable”) possible, andunique signal processing techniques increase sensitivity of thesesystems to allow detection of trace amounts of materials on surfaces. Inoperation, UV to NIR EPS systems direct energy (in the form ofconcentrated photons) from an excitation source toward a target areausing, for example, reflective or refractive optics. Photoelectric andother interactions of the photons with the sample material producedetectable wavelength-shifted emissions that are typically at longerwavelengths than the absorbed excitation UV to NIR photons, and specularreflection or absorption produces selected wavelength-specific portionsof the originating energy.

The first process involves a wavelength shift that is due to an energytransfer from the incident photons (at a specific wavelength) to thetarget materials. The transferred energy causes some of the sample'selectrons to either break free or enter an excited (i.e., higher) energystate. Thus, these excited electrons occupy unique energy environmentsthat differ for each particular molecular species being examined.

As a result, electrons from higher energy orbital states “drop down” andfill orbitals vacated by the excited electrons. The energy lost by theelectrons going from higher energy states to lower energy states resultsin an emission spectrum unique to each substance. When this processoccurs in a short time, usually 100 nanoseconds or less, the resultantphoton flux emission is referred to as fluorescence, althoughluminescence, phosphorescence, and photoluminescence are frequently usedto describe these processes as well.

The second process involves scattering of the incident energy by thetarget material due to its vibrational state; this process is known asRaman scattering, and occurs in a relatively narrow band of wavelengthsthat result from the incident energy being in the correct range toexcite the phenomenon. The third component of EPS involves specularreflection or absorption from the surface of the target material so thatonly selective portions of the incident energy spectrum are reflected,while others are absorbed.

The resultant emission spectrum generated is detected with aspectrograph, digitized and analyzed (i.e., wavelength discrimination)using unique algorithms and signal processing. Each different substancewithin the target area produces a distinctive spectrum that can besorted and stored for comparison during subsequent analyses of known orunknown materials.

UV to NIR EPS does have some drawbacks. First, it can be affected byinterference (or clutter). Interference is defined as unwanted UV to NIRflux reaching the detector that does not contribute directly to theidentification of a material of interest. For example, when attemptingto detect illegal substance on clothing, clutter can arise from excitingunimportant molecules in the target area, exciting materials close tothe detector/emitter region, external flux from outside the target area(including external light sources like room lights or the sun) andscattering from air and/or dust in the light path.

UV to NW EPS systems also are limited in terms of sensitivity distances.Greater distances between the substance of interest and the UV to NIRexcitation source and detector result in weaker return photon flux(i.e., weaker, if any, EPS) from the sample material.

Conventional spectroscopy and detection techniques include, among otherthings, neutron activation analysis, ultraviolet absorption, ionmobility spectroscopy, scattering analysis, nuclear resonance,quadrupole resonance, near infrared (NIR) reflectance spectroscopy,selectively-absorbing fluorescent polymers, and various chemicalsensors. Each of these methodologies, however, suffers fromdeficiencies.

For example, neutron activation analyses, while capable of directlymeasuring ratios of atomic constituents (e.g., hydrogen, oxygen,nitrogen, and carbon) require bulky energy sources that have high powerdemands and thus do not lend themselves to handheld instruments.Traditional UV to NIR absorption and scattering techniques are subjectto high degrees of inaccuracy (i.e., false alarms and omissions) absentsizeable reference resources and effective predictive analysis systems.Scattering analysis techniques suffer similar shortcomings.

Ion mobility spectroscopy devices are currently in use at many airportsfor “wiping” analysis, but suffer from low sensitivities in practicalmeasuring scenarios and have high maintenance demands. Resonance Ramanis an emerging and promising technology, but requires special surfacesand sample preparation for operation. Quadrupole resonance techniquesoffer a good balance of portability and accuracy, but are only effectivefor a limited number of materials (i.e., they have an extremely smallrange of materials they can reliably and accurately detect). Thesesystems also suffer from outside interfering radio frequency sourcessuch as terrestrial radio broadcast stations.

Finally, chemical sensors such as conventional NIR devices, while veryaccurate, are slow acting, have extremely limited ranges, and are toobulky for convenient handheld operation. Furthermore, chemical vaporsensors do not always produce consistent results under varyingenvironmental conditions (e.g., high humidity and modest air currents)when substantial standoff distances are involved.

SUMMARY OF THE INVENTION

The invention relates generally to the field of substance and materialdetection, inspection, and classification at wavelengths betweenapproximately 200 nm and approximately 1800 nm. In particular, ahandheld Enhanced Photoemission Spectroscopy (“EPS”) detection systemwith a high degree of specificity and accuracy, capable of use at smalland substantial standoff distances (e.g., greater than 12 inches) isutilized to identify specific controlled substances and their mixturesin order to provide information to officials so that determinations canbe made as to the legality and/or hazardous nature of such substance(s).

Thus, the invention relates to a handheld system, process, and methodfor material detection, inspection, and classification. In particular,the invention includes a miniature electronic scanning detection system(e.g, an EPS spectrograph) with a high degree of specificity andaccuracy, operating generally in the ultraviolet to near infraredportion of the electromagnetic spectrum that is used to identifyspecific individual and unique mixtures of substances (including remote,real-time measurements of individual chemical species in complexmixtures).

The unique spectral emissions from common controlled substances allowthe process to be applied to materials such as narcotics, illicit drugs,explosives, and toxic chemicals have also been observed with models ofthis instrument. The substances may additionally include food types,synthetic drugs, prescribed narcotics, liquids, powders and the like.

The invention provides a highly specific detection approach thatdirectly addresses two major classes of technical challenges: (1)standoff detection of low levels of substance deposition on or under avariety of surfaces in highly variable circumstances with (2) anextremely low false alarm rate.

Miniaturizing an EPS detection system to a handheld unit sizes involvessignificant technological and engineering improvements over presentlyavailable spectrometer systems and light sources. For example, recentlydeveloped and commercially available light emitting diodes (LED's) canprovide the necessary illumination and a bandpass filter of the properwavelength can be utilized in front of the LED, so that only themolecules of interest are excited (the physical beam pattern of theseLED's is such that two LED's, rotated so that their beam patterns areorthogonal to other, may be used for uniform illumination of the targetof interest).

Additionally, the miniaturization of spectrometer components usuallyreduces overall sensitivity, so in order to increase the systemsensitivity to the required level for trace detection of materials, alow-pass spectral filter (such as that illustrated herein) can beintroduced into the receiving optical path prior to the spectrometer.This introduction of a low-pass spectral filter reduces unwanted lightfrom the external environment, e.g., sunlight reduction for the UVimplementation of this invention, as well as narrows the spectralbandwidth to improve the signal to noise ratio. Increases in signal tonoise ratio can also be realized from suitable digital filteringtechniques.

Further, modulating the light source(s) and utilizing phase sensitive(synchronous) detection along with advanced algorithms further improvesthe signal to noise ratio, which is directly related to the limit ofminimum detection as well as the false positive rate. Improved signal tonoise ratios, along with additional signal processing (algorithmsinclude, but are not limited to, correlation, matched filters, meansquared error, and likelihood ratio comparisons) enhances detection aswell.

The invention includes a handheld EPS detections system including (a) aminiature scanning detection system operating in the ultraviolet to nearinfrared portion of the electromagnetic spectrum that includes (i) anexcitation light source; (ii) a bandpass filter; (iii) a low-passspectral filter; and (iv) an ultraviolet fluorescence detector; (b) aprocessor coupled to the ultraviolet fluorescence detector, theprocessor receiving spectral data from the ultraviolet fluorescencedetector; and (c) a database coupled to said processor that includessignature data for a plurality of predetermined chemical substances.

In another aspect, the invention includes an EPS detection system thatcan include a concentrator including a vacuum device (e.g., portablevacuum cleaner) operatively coupled to the EPS detections system withfilter material over the intake to draw particles from the environmentsurrounding the area of interest and where a filter is then used as thetarget. This arrangement facilitates detection of airborne particles ofthe material of interest.

In another aspect, the EPS detection system of the invention emits lightfrom single or multiple light sources, such as from an LED, laser, laserdiode or flashlamp, to excite emission in different substances as wellas exciting different emissions in the same substance. The light sourcemay be pulsed, square-wave modulated, and/or continuous wave and mayinclude single and/or multiple sources for complete scene illumination(e.g., rotate LED's, etc.).

In another aspect, the EPS detection system of the invention gathersspectral signatures with a spectrally selective detector, includingconventional spectrometers, spectrally filtered photodetectors,spectrometers using Multimodal Multiplex Spectroscopy™, or any otherform of spectral detection. In another aspect, the EPS detection systemof the invention digitizes the obtained spectral signatures.

In another aspect, the EPS detection system applies unique algorithmsfor signal processing, including, but not limited to, embeddedprocessors using filtered FFT, synchronous detection, phase-sensitivedetection, digital filters unique to each particular substance beingdetected. It is important to note that one, two, or all three physicalprocesses (photoemission, Raman scattering, or specular reflection orabsorption) may be present in a particular detection scenario. When onlytotal return energy in a specific band of wavelengths is being utilizedto detect the target material, then all three processes produce thetotal measured spectral energy in the wavelength band and the totalreturn signal amplitude in a range of wavelengths can produce thedesired signal for analysis and display.

When more specificity is required, a frequency-space data transformationfollowing digitization (e.g., FFT) allows the influence of each of thethree processes to be separated by examining the individual coefficientsof the transform series. Because certain coefficients are affected moreby one process than another in this type of transform, deconvolution ofthe process creating the overall spectrum is possible.

In another aspect, the EPS detection system of the invention usesalgorithms to compare the obtained spectral signatures to a database ofknown and/or previously obtained spectral signatures. These algorithmscan include, but are not limited to, correlation, matched filters, meansquared error, Laplace transforms, Fourier transforms, least-squares, orlikelihood ratio tests.

In another aspect, the EPS detection system of the invention displaysthe obtained spectral signatures and/or the results of a comparison ofthe obtained spectral with signatures to a database of known and/orpreviously obtained spectral signatures. In another aspect, the EPSdetection system of the invention includes a handheld and/or batteryoperated device EPS detection device. In another aspect, the EPSdetection system of the invention includes a GPS locater internallymounted within the EPS detection system and/or in a handheld componentof such system.

In another aspect, the EPS detection system of the invention determinesthe distance to target in order to keep the system within a sensitiverange and could adjust the detection threshold as a function ofdistance. In another aspect, the EPS detection system of the inventioncommunicates wirelessly to a remote location. In another aspect, the EPSdetection system of the invention includes cell phone and/or otherremote access communications capabilities, including video functions andstorage.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide further understandingof the invention and constitute a part of the specification. Thedrawings listed below illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention, as disclosed by the claims and their equivalents.

FIG. 1A illustrates a detection system used as a hand-held deviceaccording to the disclosed embodiments.

FIG. 1B illustrates another detection system also used as a hand-helddevice according to the disclosed embodiments.

FIG. 1C illustrates another detection system also used as a portabledevice according to the disclosed embodiments.

FIG. 2 illustrates a low-pass spectral filter detection system accordingto the disclosed embodiments.

FIG. 3 illustrates a flowchart for matching measured photoemission datawith known signature spectra of certain compounds according to thedisclosed embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Aspects of the invention are disclosed in the accompanying description.Alternate embodiments of the present invention and their equivalents aredevised without parting from the spirit or scope of the presentinvention. It should be noted that like elements disclosed below areindicated by like reference numbers in the drawings.

The invention relates to a system and methods for material detection,inspection, and classification. In particular, an electronic scanningdetection system (e.g., an EPS spectrograph) with a high degree ofspecificity and accuracy, operating in the ultraviolet to near infraredportion of the electromagnetic spectrum, is used to identify specificindividual and unique mixtures of substances (including remote,real-time measurements of individual chemical species in complexmixtures).

Preferably, the substances identified by the invention are exposedmedications and/or explosive and/or illegal materials that are nototherwise labeled or hidden within a sealed, opaque container. Certainembodiments of the invention, however, may be able to detect substancesin a cup, bottle, or other container. This feature may be desirable forquality assurance programs to evaluate and monitor substances beforeleaving a manufacturing facility or pharmacy prior to delivery.

The invention may be configured in any number of ways, including as ahand-held device, a mobile device and/or fixed mounted device. In oneembodiment, the invention is capable of electronically scanningsubstances directly or of receiving data from an accessible scanningdevice. In one embodiment, identification of a substance includesanalysis of the substance's electromagnetic spectrum. A generatedspectrum can be cross-correlated and analyzed by comparison againstother known reference information (e.g., other drugs or substances beingadministered to a patient in view of known genetic or health factors,known drug interactions and/or quality assurance information). Thedisclosed embodiments are usable without changing the physicalappearance or chemical composition of the substances.

The invention has an extensive number of applications. A non-exclusivelist includes, but is not limited to: any industries, processes and/orequipment requiring remote, non-invasive sensing of multiple chemicalcompounds or constituents (such as monitoring, commercial drug qualitycontrol and/or medication dispensing verification), Reliable detectionof trace amounts of controlled substances is required in a variety ofsettings because the raw ingredients to manufacture these substances arewidely available, and currently no detection exists that is rapid,non-contact, and handheld.

The detection systems shown in FIGS. 1A-C may include a miniature flashlamp with spectral filtering to provide the appropriate excitationenergy to induce (simultaneously) photoemission, Raman scattering, andNIR absorption/reflection in the target.

In order to improve the standoff distance and the size of the footprintof the detector, a source with more effective power in the requiredexcitation spectral band will be used. Candidates include lasers, laserdiodes, light emitting diodes, and more powerful flash lamps. Commerciallight emitting diodes (LEDs) are beginning to be available that canprovide energy on the target that is approximately 100 times greaterthan conventional energy sources. As such, the same detection thresholdthat is used in the present detector can be maintained while increasingthe standoff distance from approximately 2 inches to approximately 12inches and the effective detection footprint can be increased fromapproximately 1 inch to approximately 2¾ inches.

In the disclosed system, detection of the return photoemission iscurrently accomplished using a miniature custom spectrometer. While thisapproach allows straightforward re-configuration to detection ofemission from additional substances at other wavelengths, several otherschemes can provide sufficient spectral detection include individualphotodiode detector/spectral filter combinations as well as lower costand smaller size spectrometer designs. The resolution of the currentspectrometer is greater than is required for this application, so thespectrometer approach may prove viable in a lower-resolution version.

The invention can include any known scanning device or combinationsthereof. Computer and control electronics can also be connected to orused in tandem with the invention. The invention includes a handheld EPSdetections system including (a) a miniature scanning detection systemoperating in the ultraviolet to near infrared portion of theelectromagnetic spectrum that includes (i) an excitation light source;(ii) a bandpass filter; (iii) a low-pass spectral filter; and (iv) anultraviolet fluorescence detector; (b) a processor coupled to theultraviolet fluorescence detector, the processor receiving spectral datafrom the ultraviolet fluorescence detector; and (c) a database coupledto said processor that includes signature data for a plurality ofpredetermined chemical substances.

The disclosed systems may include an optical scanning device, aspectrograph (if this technique is used), a detector and an energysource. The disclosed system also may include a scanning device that isportable and/or that has no input keyboard or monitor screen. In thisembodiment, the scanning detection device communicates using an inputspectrograph and an output of a series of lights (e.g., green, yellow,blue, red and the like) mounted on the scanning device.

The disclosed system also may include an EPS detection system that caninclude a concentrator for airborne materials comprising a vacuum device(e.g, portable vacuum cleaner) operatively coupled to the EPS detectionssystem with filter material over the intake to draw particles from theenvironment surrounding the area of interest and where a filter is thenused as the target. The EPS detection system of the invention emitslight from single or multiple light sources, such as from an LED, laser,laser diode or flashlamp, to excite emission in different substances aswell as exciting different emissions in the same substance. The lightsource may be pulsed, square-wave modulated, and/or continuous wave andmay include single and/or multiple sources for complete sceneillumination (e.g., rotate LED's, etc.).

The EPS detection system of the invention may gather spectral signatureswith a spectrally selective detector, including, for example,conventional spectrometers, spectrally filtered photodetectors,spectrometers using Multimodal Multiplex Spectroscopy™, or any otherform of spectral detection. In another aspect, the EPS detection systemdigitizes the obtained spectral signatures. The EPS detection systemapplies unique algorithms for signal processing, including, but notlimited to embedded processors using filtered FFT, synchronousdetection, phase-sensitive detection, digital filters unique to eachparticular substance being detected.

The EPS detection system compares the obtained spectral signatures to adatabase of known and/or previously obtained spectral signatures. Inanother aspect, the EPS detection system of the invention displays theobtained spectral signatures or the results of a comparison of theobtained spectral with signatures to a database of known or previouslyobtained spectral signatures.

The EPS detection system may include a handheld or battery operateddevice EPS detection device. The EPS detection system also may include aGPS locater internally mounted within the EPS detection system or in ahandheld component of such system. The EPS detection system determinesthe distance to target in order to keep the system within a sensitiverange. The EPS detection system also may communicate wirelessly to aremote location. The EPS detection system may include cellular or otherremote access communications capabilities.

In general, the disclosed system provides a mechanism for collectingunique “fingerprint” identifications (i.e., gathers information suchthat the fingerprint may be determined in a timely manner) of targetmaterials that are used to distinguish them from other similarsubstances without prior knowledge of the substance (i.e., no single“unique identifiers” required). The fingerprint may include anyquantifiable characteristic(s) pertaining to the substance, such asexcitation wavelengths, barcodes, electronic signatures, and the like,negating any requirement for a single unique identifier. The disclosedsystem also may include an accessible database of knowncharacteristic(s) pertaining to certain agents and substances. Anaccessible computer system or other storage means enables the time,place and type of substance administered to be documented.

A broadband source may be used to generate EPS within a target areacausing detectable emission at UV to NIR wavelengths that can beuniquely matched to known materials.

In another embodiment of the invention, the system can be used tosimultaneously evaluate a group of different substances' for example,methamphetamine and TATP explosive. In this embodiment, the operator canbe permitted to manipulate a combined spectrum of a group of differentpowders, or other chemical substances, and use the combined spectra toidentify unauthorized or inappropriate variations. Such variations caninclude dangerous mixtures of partially completed mixes or additionsand/or quality control verifications. Spectra of individual substancescan also be combined to identify specific substances such aspharmaceuticals and explosives.

The detection of emission photons is accomplished with a receiver thatincludes optics, a spectrograph, and a detector array. The disclosedsystem may include an analysis system that identifies particularsubstances of interest. The disclosed system preferably operates withinthe UV to NIR radiation wavelength range of approximately 200 nanometersto approximately 1800 nanometers. The disclosed system, however notlimited to this wavelength range as the invention can operate withinother wavelength ranges.

Multispectral excitation and/or detection is accomplished with theinvention in a number of ways. Selection and control of eitherexcitation wavelengths and/or detection wavelengths can be accomplishedusing, among other things, a pulsed power sources (e.g a sequence-pulsedlaser system) in conjunction with data collection corresponding to eachpulse, a spectral filter wheel(s) to select or vary different excitationor detection wavelengths and combinations thereof. The commercialavailability of LED's allows miniaturization and power consumptionoptimization of the handheld system.

The features disclosed above may be incorporated within a detectionsystem. Examples of hand-held or stand-alone detection systems are shownin FIGS. 1A-C. FIG. 1A depicts a detection system 10 used as a hand-helddevice according to the disclosed embodiments. Detection system 10includes housing 12 which includes the electronics and components toperform the detection functions. These elements are disclosed in greaterdetail below.

Detection system 10 also includes hand grip 14 below housing 12. Handgrip 14 may house the power supply or batteries for detections system10. The front of housing 12 includes through-holes 16 that allow lightor energy to be directed and captured when detection system 10 is inoperation. Detection system 10 may include additional through-holes asneeded.

Housing 12 of detection system 10 also may include a compartment toreceive cartridge 18. Cartridge 18 may store data for detectingspecified substances so that detection system 10 does not require awireless or remote connection. This feature may be desired in thoseareas where wireless networks do not exist, yet the need for a portablesystem exists. Cartridge 18 may house a hard-drive or other means forstoring the database for spectral signatures. Cartridge 18 also maystore instructions to operate detection system 10. Cartridge 18 also maybe placed in the top of detection system 10, or within hand grip 14.

FIG. 1B depicts a detection system 20 also used as a hand-held deviceaccording to the disclosed embodiments. Detection system 20 includes ahousing 22 and hand grip 24, much like detection system 10. Housing 22,however, differs from housing 12 in that it slopes downward away fromthe user, and is smaller to fit within cramped areas. Detection system20 may be used in buildings or in security operations involvingcompartments such as airplanes, trains, ships or automobiles. The usermay place detection system 20 within the compartment to detectsubstances on the floor or bottom of the compartment.

Detection system 20 also includes back panel 25 that provides visualindication to the user of the results of detection operations. Scanbutton 26 may initiate detection operations. Power button 28 togglesdetection system 20 on and off, with an “on” state being shown by powerindicator 29. Indicator 30 may show that detection system 20 isoperating and in the process of receiving signals back from the targetsubstance. Bar indicator 32 may show the intensity level of the receivedsignals back to detection system 20. If the levels are not high enough,then detection operations may be re-initiated. Indicator 34 shows thatthe target substance matches the spectral data of a substance ofinterest, such as explosives or drugs.

FIG. 1C depicts a detection system 40 used as a portable deviceaccording to the disclosed embodiments. Detection system 40 includeshousing 42 and front part 44. Detection system 40 does not include ahand grip, and is similar in size to a personal digital assistant.Ridges 49 help distinguish detection system 40 from other devices thatthe user may handle.

Front part 44 includes an aperture for allowing a light source 110 tosend a beam of light towards a target. The light is reflected off thetarget, and received at detector screen 46. The internal components ofdetection system are disclosed in greater detail below. Front part 44may be removable from housing 42 so that different filters may be usedto detect different materials.

The internal components for the disclosed detection systems may form alow-pass spectral filter system, such as the system 100 illustrated inFIG. 2. The system disclosed by FIG. 2 can be utilized in detectionsystems 10, 20 and 40 disclosed above. In particular, FIG. 2 illustratesthe use of shutters and/or mechanical baffles minimizes extraneous lightsources by selectively limiting access of extraneous light (as well asexcitation and emission light) to the detector. For example, a shutterwithin housings 12 and 22, or front part 44 may be triggered to openwithin a discreet period of time in conjunction with an excitation pulsein order to limit the interference effects of extraneous light sources.

FIG. 2 depicts the components for a low-pass spectral filter detectionsystem 100 according to the disclosed embodiments, System 100 may beincorporated within the hand-held and portable detection systemsdisclosed above. In particular, the components disclosed by FIG. 2 maybe housed within the detection systems disclosed above.

In FIG. 2, excitation energy 102 from one or more excitation (i.e.,light) sources 110 within detection system 100 is directed through aspectral filter 140 at a target material 112 in order to generate anemission. Although two light sources 110 are shown, the disclosedembodiments may include any number of excitation sources, includingusing only a single light source. Preferably, light source or sources110 may produce narrow-band energy of about 10 nanometers or less. Morepreferably, the narrow-band energy is about 3 nanometers or less. Lightsources 110 may be turned on and off quickly, such as in a range ofabout or less than 0.01 of a second. Preferably, light sources 110 maybe turned on and off within a time period of about 0.001 second.

Emission energy 104 from the targeted material is detected with an optic114 and is enhanced by a connected low-pass spectral filter 116 prior tobeing analyzed by a coupled spectrograph/spectrometer 120. Visible lightfilter 113 may be located in front of optic 114. Visible light filter113 helps prevent a large spectrum of light from entering the system sothat the large spectrum does not overload the subsequent components withinformation.

Spectrometer 120 is coupled to synchronous detector 121. Synchronousdetector 121 is on when light sources 110 are on. Preferably, a returnsignal of emission energy 104 is received and processed when lightsources 110 are on. A problem with optical methods of substancedetection is that unwanted light may enter detection system 100. Becauseof the sensitivity of the components of detection system 100, unwantedlight may interfere with the desired light response resulting from lightsources 110 (or any illumination source).

Light sources 110 may be modulated within a range of about 100 Hz to3000 Hz to insure that the response, such as emission energy 104, fromtarget material 112 is the predominate signal received by synchronousdetector 121. Synchronous detector 121 is synchronized to this lightmodulation in phase and frequency. Thus, detection system 100 respondsto the desired substance response while rejecting light of otherfrequencies and phases outside the narrow passband invoked by thefilters of detection system 100. Moreover, a detector “on” during theentire process would pick up shakiness or other movements of detectionsystem 100. The disclosed embodiments help mitigate such interference.

Synchronous detector 121 is coupled to integrator 119. The signaldetected by synchronous detector 121 is rectified for furtherprocessing. Integrator 119 rectifies the AC signal from synchronousdetector 121 to a corresponding DC signal or signal with a DC component.The rectification of the signal helps extract the data within thedetected signal by subsequent components of detection system 100.

After being rectified by synchronous detector 121 and integrator 119,the resulting data signal is processed and digitized with a digitizer122. Alternatively, digitizer 122 may receive a voltage signalindicative of the data signal received by spectrometer 120. Signalprocessor 134 receives and further processes the digitized data, andprovides it other components within detection system 100. The collecteddata may be imaged on a display 124 or reported (e.g., by abuzzer/audible device or a display light) by alert 126.

Detection system 100 also may include a camera 128 for visuallyrecording the target material 112. Detection system 100 also may includevarious communication devices 132 (e.g., a cell phone, GPS module, awireless interface) as well as a data storage mechanism. These devicesmay transmit and receive information from other sources, and be used tobackup information detected and generated by detection system 100.Devices 132 also may be modular in that they are separable fromdetection system 100 as needed.

Detection system 100 also may include a distance sensor 130 formeasuring the offset distance of the device from the targeted material.Red passband filter 131 is located between distance sensor 130 andtarget material 112. Distance sensor 130 may provide different resultsdue to different surfaces within target material 112. Red passbandfilter 131 filters light received to narrow the spectral bandwidth, andto reduce these differences. Red passband filter 131 also may be knownas an optical distance filter.

Distance sensor 130 provides distance to target information fordetection system 100. Thus, detection system 100 may keep the detectionthreshold approximately constant over a period of time by accuratelysetting the system gain in real-time. Errors in distance determination,therefore, may result in fluctuations in the detection threshold andpossible false alarms or non-detects. Red passband filter 131 helpsprevent such errors. Moreover, an output of distance sensor 130 is usedto adjust an indicator for 1/R² energy falloff, where R is thedetermined target-to-system distance. The indicator may be used to alerta user that the distance between detection system 100 and targetmaterial 112 may result in an erroneous reading.

To provide better distance determination results, an angle 152 between acentral ray 150 from light source 110 and an optical axis is adjustableto reduce energy from non-Lambertian surface reflections from unwantedsubstances or surfaces. Not every surface of target material 112 issmooth and reflective, and this feature allows detection system toaccount for such reflections that may distort analysis by subsequentcomponents.

Thus, the output of synchronized detector 121 may be rectified,processed and filtered to produce a resultant DC voltage thatconstitutes the response from target material 112. This signal fromsynchronized detector 121 is digitized or compared to a fixed voltage toprovide an indication of detection or non-detection of a substance ofinterest.

Regardless of the particular configuration, the sensitivity limits ofthe system can depend on any of several factors. These factors caninclude: energy source availability, cross-section of photoelectricabsorption, path length, detector collecting area, detector spectralresolution, detector geometrical characteristics, integration time, anddetector noise limit. A number of steps have been taken to maximizethese factors for detection.

The disclosed system may use a continuous output deuterium ultravioletsource with narrow-band interference filter(s) to define the excitationspectral properties. In such an arrangement, the power density availableat full output power is 1 mW/cm². The UV to VIS output is collected by a3 cm² area lens and directed from the target area to the detectionsystem. The lens collects energy from a concentrated illuminated spot(about 100 mm diameter) on a target at an approximately 300 mm standoff.

The cross-section of the target is optimized for photoelectricabsorption by selecting a fixed spectral filter or by using amonochromator to provide the required excitation wavelength for eachsubstance of interest in the target area. Simultaneously, a receivercomprising a spectrograph and light-sensitive detector views the targetarea. Thereafter, quick emission samples (or exposures) are recorded andthe resultant spectra compared to a database of known substances. Usingthis system, detection sensitivities of approximately 100 nanograms/cm²with methamphetamine have been achieved in a 2 inch diameter area at astandoff distance of 12 inches.

The disclosed system also provides the ability to detect and analyzesubstances within target areas at substantial standoff distances whetherin liquid, solid or gaseous form. The disclosed system also may beadapted to be use in unique and varied system configurations (includingcritical component placement). The disclosed system includes thecreation, update and maintenance of a database of unique signatures forindividual and complex mixtures of substances. In this regard, theinvention can utilize miniature spectrograph instruments coupled todetector arrays with high efficiency power capabilities and novel sourceoptics design.

The disclosed systems include hand held devices for the detection ofunknown substance, including, for example, methamphetamine and itschemical precursors. These embodiments of the invention enable real timedetection of illicit drugs and illicit drug production. Detection ofmethamphetamine, for example, is accomplished by passing the spectralbeam over a surface contaminated with trace quantities ofmethamphetamine. In this regard, the invention is well suited foraddressing issues related to the illicit production and distribution ofamphetamine and amphetamine-like substances.

For example, illegal laboratories that manufacture methamphetamines areone of the greatest challenges facing law enforcement officers.Remediation of methamphetamine laboratories is a required step prior topermitting re-occupancy of the house or other contaminated structurewhere an illicit lab was located because residual chemicals may posehealth concerns in residential structures even after the laboratoryequipment has been removed.

FIG. 3 depicts a flowchart 300 for matching measured photoemission datawith known signature spectra of certain compounds according to thedisclosed embodiments. In FIG. 3, step 301 executes by initializing thedetection system, such as detection system 100. Step 302 executes byinputting sample data. The data from an evolving sample spectrum beingacquired is supplied to the system. Step 304 executes by synchronouslyrectifying the signal received by detection system 100. The signalsreceived by synchronous detector 121 are rectified.

Step 306 executes by digitizing or performing analog signal processing.Detection system 100 may apply algorithms to the acquired sample data.This step can include, for example, application of a 20th order powerseries of cosine functions for curve matching or an FFT analysis.

Step 308 executes by comparing the rectified or digitized signal to theUV signatures loaded from a database. Step 308 can include, for example,using a least-square curve-fitting routine or FFT that reduces themeasured spectrum to a small set of digital numbers sufficient todescribe the key information contained in the spectrum, including usingup to a 24th-order equation to manipulate the digitized information (orits coefficients if transformed to frequency space by an FFT).

Step 310 executes by defining matches based on preset or user-selectedvariances. Detection system 100 determines whether there has been amatch based on the comparison procedure in step 308. A match can bedefined as a preset standard deviation between values from the samplespectrum and those of stored spectra, such as, for example, threestandard deviations above or below an average value of a storedspectrum).

Step 312 executes by outputting spectral match results. Detection system100 outputs the results of any matches. Step 312 can include either (orboth) of steps 314 (in which the system provides spectral results forvisual inspection by the operator and/or provides overlays of theproduced spectra) and step 316 (in which visual and/or audible alarmsindicate a match). Step 314 executes by entering an identification mode,as disclosed above. Step 316 executes by entering a verification mode,also disclosed above.

The disclosed embodiments allow for an extensive number of applications.A non-exclusive list includes, but is not limited to: any industries,processes and/or equipment requiring remote, non-invasive sensing ofmultiple chemical compounds or constituents (such as in the chemical,petroleum and other similar industries, internal pollution andcontamination controls, external pollution and contamination controls,illegal drug detection and monitoring, commercial drug quality controland dispensing verification, nuclear waste and effluent monitoring, airstandards determination, explosives monitoring and detection,semiconductor industry effluent monitoring and control, hazardous wasteand emission monitoring, semiconductor quality control measures,semiconductor processing contamination monitoring and control, plasmamonitoring and control, waste dump site monitoring and control, nuclear,biological, and chemical weapons by-products monitoring, clean roommonitoring and control, clean room tools monitoring, vacuum controls,laminar flow controls and controlled environments); security monitoring(including airport and transportation security, improvised explosivedevice (IED) detection, military and civilian ship and buildingsecurity, drug (illegal and commercial) security, explosives, weaponsand bio-hazard manufacture, detection and storage); remediation(including of hazardous and toxic materials, chemicals, buried landmines, unexploded ordinance, and other explosive devices).

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the disclosed embodiments ofthe privacy card cover without departing from the spirit or scope of theinvention. Thus, it is intended that the present invention covers themodifications and variations of the embodiments disclosed above providedthat the modifications and variations come within the scope of anyclaims and their equivalents.

What is claimed is:
 1. A handheld photoemission spectroscopy detectionsystem comprising: a miniature scanning detection system operating inthe ultraviolet portion of the electromagnetic spectrum comprising anexcitation light source to generate excitation energy including acentral ray, wherein the excitation light source is modulated within arange of about 100 Hz to 3000 Hz, an ultraviolet fluorescence detectorto detect a plurality of emissions produced by the excitation energy,and a synchronous detector synchronized to a phase or a frequency of theexcitation light source to detect a signal of interest from theplurality of emissions; a distance sensor to determine a distance to atarget of the plurality of emissions based on the signal of interest; aprocessor coupled to the synchronous detector, the processor receivingspectral data from the signal of interest; and a database coupled tosaid processor that includes signature data for a plurality ofpredetermined chemical substances to compare to the spectral data. 2.The handheld photoemission spectroscopy detection system of claim 1,wherein the miniature scanning detection system further includes alow-pass spectral filter.
 3. The handheld photoemission spectroscopydetection system of claim 1, wherein the miniature scanning detectionsystem further includes a visible light filter.
 4. The handheldphotoemission spectroscopy detection system of claim 1, furthercomprising a camera.
 5. The handheld photoemission spectroscopydetection system of claim 1, further comprising a red passband filterconfigured in front of the distance sensor.
 6. The handheldphotoemission spectroscopy detection system of claim 1, wherein outputof the distance sensor is used to determine that a target of theexcitation energy is too far away.
 7. The handheld photoemissionspectroscopy detection system of claim 1, wherein the excitation lightsource comprises at least one of a light emitting diode, a laser, alaser diode, a flashlamp and combinations thereof.
 8. A handheldphotoemission spectroscopy detection system comprising: a miniaturescanning detection system operating in the ultraviolet portion of theelectromagnetic spectrum comprising an excitation light source to directexcitation energy at a target, wherein the excitation light source ismodulated within a range of about 100 Hz to 3000 Hz; an optic to detectemission energy from the target; an ultraviolet fluorescence detector todetect a plurality of emissions from the emission energy; a synchronousdetector to detect a signal of interest from the plurality of emissions;a processor coupled to the synchronous detector, the processor derivingspectral data from the signal of interest; a distance sensor todetermine a distance to the target; and a memory coupled to theprocessor that includes signature data to store a plurality ofpredetermined substances to compare to the spectral data.
 9. Thehandheld photoemission spectroscopy detection system of claim 8, furthercomprising a low-pass spectral filter to enhance the emission energy.10. The handheld photoemission spectroscopy detection system of claim 8,wherein the synchronous detector is in an “on” state when the excitationlight source is in an “on” state.
 11. The handheld photoemissionspectroscopy detection system of claim 8, further comprising anintegrator to rectify the signal of interest to a direct current (DC)signal or a signal with a DC component.
 12. The handheld photoemissionspectroscopy detection system of claim 8, further comprising displaymeans to provide visual indication of the comparison to the spectraldata and the distance to the target.
 13. The handheld photoemissionspectroscopy detection system of claim 8, further comprising an opticaldistance filter coupled to the distance sensor.
 14. A method fordetecting a substance using a handheld photoemission spectroscopydetection system, the method comprising: generating excitation energywith an excitation light source; directing the excitation energy at atarget having an offset distance; detecting a plurality of emissionsfrom the target with an ultraviolet fluorescence detector; determiningthe offset distance to the target using a distance sensor using theplurality of emissions; detecting a signal of interest from theplurality of emissions using a synchronous detector; retrievingsignature data for a predetermined chemical substance based on thesignal of interest; and displaying the signature data.
 15. The methodfor detecting a substance of claim 14, further comprising filtering theplurality of emission using an optical distance filter located betweenthe distance sensor and the target.
 16. The method for detecting asubstance of claim 14, further comprising adjusting an angle between acentral ray of the excitation light source and an optical axis.
 17. Themethod for detecting a substance of claim 14, further comprisingadjusting an indicator for energy falloff using output from the distancesensor.